Heretofore, various devices have been used for grinding material to be ground such as stone, silica, foodstuff and the like. For example, impact mills, roll mills, tumbling ball mills, vibrating ball mills, and the like, are representative devices, and particularly, as a device for fine grinding, the tumbling ball mill or vibrating ball mill have been used in many cases.
The conventional tumbling ball mill is constructed in such a way that material to be ground is charged into a grinding vessel loaded with a grinding medium, and the grinding vessel is rotated so as to grind the material to be ground by the grinding medium by means of gravity. Similarly, the conventional vibrating ball mill has such a construction as to improve the grinding effect of the tumbling ball mill by giving a high intensity vibration to the grinding medium.
However, since the conventional tumbling ball mill was dependent only upon gravity with respect to its grinding operation, in order to make the grain size of the material to be ground smaller, it was necessary to make the diameter of the grinding vessel to be extremely large and to expend an extremely long grinding time.
In addition, while the vibrating ball mill eliminated the problem of the increased diameter of the grinding vessel and its mounting base as well as the long grinding time of the grinding medium by means of the high intensity vibrating effect, the power required was quite great in view of the mill construction, and the consumption of power became excessive, both characteristics of which proved to be operational problems.